Cyber Resilience

CVE-2023-20244

Cisco Secure Firewall Threat Defense 6.2.3 … 7.3.1.1

Published
01 November 2023
Modified
11 August 2026
Patch / advisory
View advisory
CVSS Score v3.1 8.6
Click a component to see what it means
Raw vectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
EPSS Score 0.0077 53th percentile
Risk Priority 63 floored blend · peak EPSS

Summary

CVE-2023-20244 is a high-severity Missing Reference to Active Allocated Resource (CWE-771) vulnerability in Cisco Secure Firewall Threat Defense. Its CVSS base score is 8.6 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique Endpoint Denial of Service (T1499); ranked in the top 47% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog.

EU & UK References

Vulnerability Data

A vulnerability in the internal packet processing of Cisco Firepower Threat Defense (FTD) Software for Cisco Firepower 2100 Series Firewalls could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. This vulnerability…

more

is due to improper handling of certain packets when they are sent to the inspection engine. An attacker could exploit this vulnerability by sending a series of crafted packets to an affected device. A successful exploit could allow the attacker to deplete all 9,472 byte blocks on the device, resulting in traffic loss across the device or an unexpected reload of the device. If the device does not reload on its own, a manual reload of the device would be required to recover from this state.

CWE(s)
CWE-771NVD-CWE-noinfo

Related Threats

MITRE ATT&CK Enterprise Techniques

T1499 Endpoint Denial of Service Impact
Adversaries may perform Endpoint Denial of Service (DoS) attacks to degrade or block the availability of services to users.
attack.mitre.org →
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2023-20006Same product: Cisco Firepower 2110
CVE-2024-20330Same product: Cisco Firepower 2110
CVE-2024-20311Same vendor: Cisco
CVE-2026-20106Same product: Cisco Secure Firewall Threat Defense
CVE-2026-20105Same product: Cisco Secure Firewall Threat Defense
CVE-2023-20095Same product: Cisco Secure Firewall Threat Defense
CVE-2024-20481Same product: Cisco Secure Firewall Threat Defense
CVE-2023-20086Same product: Cisco Secure Firewall Threat Defense
CVE-2026-20014Same product: Cisco Secure Firewall Threat Defense
CVE-2026-20015Same product: Cisco Secure Firewall Threat Defense

Affected Assets

cisco
secure firewall threat defense
6.2.3, 6.2.3.1, 6.2.3.10, 6.2.3.11, 6.2.3.12

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)

—

Detect
Catch it (NIST detect / respond)

—

Harden
Shrink the surface (DISA STIG)

—

Validate
Prove the fix (OWASP ASVS)
  • V7.4.5

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.PS-06 mostly match
prevents

Secure development practices directly prevent lost resource references via coding standards, reviews, and tooling.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

A.8.29 Security testing in development and acceptance mostly match
finds

Security testing can detect missing references to allocated resources before deployment.

A.8.25 Secure development life cycle partial match
prevents

Secure development lifecycle practices can include resource-management rules that prevent missing references.

A.8.27 Secure system architecture and engineering principles partial match
prevents

Secure system architecture principles can mandate explicit resource tracking and release mechanisms.

A.8.28 Secure coding partial match
prevents

Secure coding standards can require proper reference maintenance for allocated resources.

A.8.9 Configuration management partial match
degrades

Configuration management can enforce proper tracking of allocated resources and their references.

References